Campaigners for a ban on smacking children vowed today to fight on after the Lords said parents should be able to use "mild" punishment.

Peers voted last night for a compromise measure outlawing smacking that causes lasting harm, over an outright ban.

The decision was denounced as "shameful, unjust and irresponsible" as MPs prepared for a second push in the Commons.

That is likely to fail in the face of opposition from Tony Blair, whose official spokesman said before the vote: "We do not want to criminalise parents."

Peers backed the compromise measures by an overwhelming 226 votes to 91.

Liberal Democrat Lord Lester's proposals removed the defence of "reasonable chastisement" which dates from 1860. Instead they made it a criminal offence in England and Wales to cause bruises or mental harm.

The vote came as peers discussed the Children Act, aimed at increasing protection for youngsters in the wake of the Victoria Climbie case.

Lord Lester's amendment was backed by Lord Laming, who headed the inquiry into the death of eight-year-old Victoria who was abused and tortured by her great aunt and the aunt's boyfriend.

"We would all like every parent to have the skills and ability not to have to resort to physical punishment," he said.

"The reality is quite different at the present time for many parents who may be tired, may be exhausted, may be harassed for a whole variety of reasons.

"The most important thing is to pursue constructive approaches towards the family and not rather negative ones."

However, Tony Samphier, of the Children Are Unbeatable! Alliance, said the peers had failed children.

He said: "It sends out a dangerous message to society that it is still legally acceptable to assault a child.

"'Hitting children is as unacceptable as hitting anyone else, and the law should clearly say so."

The Lords were voting on a series of amendments to the Children Bill.

Labour peers had been ordered to vote against the outright ban, but were given a free vote on Lord Lester's amendment.

Senior Labour MP David Hinchliffe called for a free vote on a total ban when the Bill reaches the Commons.

Mr Hinchliffe, chair of the health select committee which has called for a ban, said 100 backbenchers and a "significant" number of ministers supported him.